A. Field of the Invention
The invention relates to a test chart, especially to a test chart printed on a calibration paper readable by an optical scanner for image quality test.
B. Description of the Prior Art
It is known that an optical scanner has to pass strict image quality tests before it can be sold on the market. The tests include horizontal and vertical scaling-up, skew, color consistency, color balance, shading, step transition, peripheral, resolution, and missing line and so on. These tests are usually done by examining an image of a test chart scanned by the optical scanner under quality testing. Since the test chart contains specially designed patterns for testing various features of an optical scanner, so from the images of the test chart, the image quality of the optical scanner can be shown easily.
Conventional test charts are usually not well organized. The data size of the test patterns is usually so large that each pattern on the test chart has to be scanned separately. And each testing is also processed separately. Consequently, the image quality test of an optical scanner consumes lots of testing time and efforts. Moreover, some test charts do not have a few important test items, such as step transition test, image skew test, and center resolution test. Besides, the patterns for identifying peripherals are usually too small to be detected.